Multiple-effect distillation is a well-established process for purifying liquids. It is particularly useful for sea-water distillation, although it can be effectively used with other chemicals, such as alcohols.
Most multiple-effect stills are made using a multiplicity of cylindrical chambers, with a separate chamber for each effect and an elaborate tubing mechanism being used to connect the effects. We disclose a rectangular configuration with a modular design which allows easy access for maintanence, is simple to construct, and has a short, efficient path for the vapor to follow as it moves from one effect to the next.
The prior art which most nearly resembles our invention is Takada et al in their U.S. Pat. No. 3,824,154. Takada provides for a bundle of horizontally oriented heat exchanger tubes in each effect. The effects are separated in part by a partition wall, which also contains a vapor passageway, and in part by the bottom surface of a preheating chamber. Takada requires his partitions to be substantially horizontal.
Takada's invention cannot be used as shown with vertical tubes. Furthermore, his invention requires a multiplicity of jet holes to be installed in his partition wall to allow distilland to flow between the effects. Furthermore, his preheating chamber must run the entire length of the tubes. This results in the vapor path being longer and more convoluted in his invention than ours, and thus subjects the vapor to greater pressure losses as it travels between effects, decreasing the energy efficiency of his distillation process as compared to ours.
My invention provides for vertical tubes with simply constructed, vertically oriented baffles separating the effects.